The present invention relates to a new and improved apparatus for controlling a winding device for a continuously supplied fiber sliver and which can be stopped or shut-down during the bobbin change operation.
With continuously supplied fiber slivers which are wound onto a bobbin by a winding device the necessity arises of effecting a bobbin change operation from time to time for exchanging a filled bobbin against an empty tube. This operation can be effected in different manner, depending upon the type of winding device employed. A suitable winding device is one provided with more than one winding spindle per winding head, for example a so-called revolver or turret head; another suitable winding device is one provided with one single winding spindle per winding head.
If there is used a known winding device provided with more than one winding spindle per winding head, the possibility exists of carrying out a so-called flying bobbin change, i.e. the winding process is not interrupted. In this case if the full diameter of the bobbin is reached, the winding spindle which is in its operating position is moved, and simultaneously a second winding spindle prepared with an empty tube is brought into operating position. This movement of two winding spindles, which in the case of a revolver head constitutes a rotary movement, can be carried out very quickly. Transfer of the fiber sliver from the full bobbin to the empty tube and tearing or breaking of the sliver connecting the two also must be effected very quickly if no interruption of the winding process is desired. The use of a winding device of this type, however, involves serious disadvantages in the winding of a continuously supplied fiber sliver.
A first disadvantage of a multi-spindle type winding device resides in the fact that it is complicated and expensive. A plurality of winding spindles is needed and the winding device must be additionally equipped with a complicated control mechanism so that each winding spindle, the position of which must be movable, can be driven while it is in its operating position.
A further disadvantage of the known multi-spindle winding device is, notwithstanding the theoretical possibility of effecting a bobbin change operation without interruption of the winding process, also here the necessity arises of providing control elements for the speed of the winding device or at least for the winding tension, since it is extremely difficult to achieve perfect synchronization of the speeds of the continuously supplied fiber sliver and the winding device and furthermore variation of the fiber sliver tension is unavoidable during the bobbin change. For this reason, there has been proposed the use of a so-called dancer or tensioning roll arranged between the last element continuously supplying the fiber sliver and the winding device, i.e. a roll permitting adaption of the fiber sliver path length within a limited range. By reciprocating the dancer roll it was possible to realize a compensation of the winding tension of the fiber sliver and/or an adaption of the winding speed of the winding device.
The application of multiple-spindle winding devices for flying bobbin change is also not possible with all types of fiber slivers due to the very short time periods available for severing the fiber sliver, e.g. difficulties prevail when severing fiber slivers of very high breaking strength, such as e.g. thick slivers of staple fibers bonded by adhesive or endless filaments at such installations.